Currently crown metal caps are made in one piece laminated with an inner and an outer face, circular and provided with a skirt around the perimeter of closure, which in turn is provided with a plurality of radial intercalated protrusions and depressions.
When applied to a bottle, the closure of the crown metal cap is airtight as the circular plane is pressed against the upper part of the bottle opening by applying the cap on it. Protrusions and depressions of the closure flange of the crown metal cap are folded and pressed at the same time by a forming tool against the bottle opening and slightly below it, providing a proper grip.
The crown metal caps can be of the type:                Metal cap “fixed” (known in English as PRY-OFF), which is one that can only be opened using a lever type opener.        Metal cap “easy open” (known in English as a TWIST-OFF), which is one that can be opened by applying a slight turn manually to cause the rotation of the same.        
The metal caps “easy open” in turn could be classified as:                Metal caps of “rough touch” which is one with a closing flange, when folded, has a surface formed by generally pointed or sharp protrusions that are somewhat uncomfortable to touch.        Metal caps of the “comfortable feel” type, which is one with a closing flange, when folded, has a surface formed by generally round or flat protrusions that are comfortable to touch.        
Examples of prior art of metal caps “easy open” of the “rough feel” type are described in the patent documents U.S. Pat. No. 5,458,253 and US-2005/029218.
Examples of prior art of metal caps “easy open” of the “comfortable feel” type are described in the patent documents CA-1,252,431, U.S. Pat. No. 3,648,874 and U.S. Pat. No. 4,337,871.
A current trend to produce metal caps “easy open” of the “comfortable feel” type is to design metal caps with a closing rim which, once it is folded to seal a mouth of a bottle, it has a larger number of protrusions than it had before being folded, as described by U.S. Pat. No. 4,337,871. However, it is very common that when a person wants to open this kind of caps “easy open” of the “comfortable feel” type with a bottle opener, the mouth of the bottle tends to break or crash, or said metal cap is damaged without opening. This problem is magnified in high-use facilities on site of beverages in bottles, such as bars, restaurants, at parties, conventions, etc., where the barman or “bartender” is forced to use a bottle opener to open sealed bottles with metal caps “easy open” to meet consumer demand, causing a high incidence of broken or crashed bottle openings, or with the metal cap damaged and remaining unopened. This problem is due to the limited space between the rim of the mouth of the bottle and the closure flange of the metal cap, which prevents a proper supporting point of the bottle opener, causing the opener to tend to this store to pull out without produce the opening of the metal cap, and thus the user tends to apply a greater force to the bottle opener with the risk of breaking or smashing the mouth of the bottle.
Now, with reference to U.S. Pat. No. 4,337,871 Raymond L. Tucker describes a “easy open” crown metal cap, which in its state prior to its closure for sealing a mouth 80 of a bottle consists of a circular plate piece and provided perimetrically of a bell-shaped closure flange formed by a plurality of protrusions 24 and depressions 25 (See FIG. 1). Each protrusion 24 has a width equal throughout its length and its width is greater than the width of each depression 25, so that when the closure flange folds over the mouth 80 of the bottle to be sealed (as shown in FIG. 2), each protrusion 24 collapses and forms a central depression 32 straight that splits the protrusion 24 in a pair of straight minor protrusions 31 to form a smooth surface of the closure flange and make the opening of the bottle easier when turning the metal cap manually. However, by folding the closure flange, each depression 25 folds in its full length over the mouth 80 of the bottle without leaving space between the rim of the mouth 80 of the bottle and the bottom rim of the folded flange, which is a problem because there is not enough space to pry a bottle opener for opening the metal cap, which is why the realization of the state of the art of the metal cap can only be opened manually when turning the cap, as when using a bottle opener the risk is run of breaking or crashing the mouth of the bottle.
In view of this, it is necessary to provide a crown metal cap that has the advantages of the opening mode “easy open” but of a “comfortable feel” type and that in turn can also be opened using a bottle opener without thereby causing damage to the mouth of the bottle which seals or the same metal cap.